In order to conventionally sew together two pieces of fabric, for instance in garment sewing, overlock sewing machines are ordinarily used to join the two pieces of fabric while avoiding fraying of fibers at the edges of the pieces of fabric. Generally, two superposed pieces of fabric, with the edges thereof aligned, are over-edge stitched at the edges, using two looper threads, while the pieces of fabric are sewn together using a needle thread (FIG. 11(a)). The appearance of the sewn-on portion resulting from such sewing by the overlock sewing machine is poor in that, although fibers are not frayed, the edges of the pieces of fabric are nevertheless still exposed. In consequence, the sewn-on portion is made non-visible from the outside by being arranged on the reverse surface of the garment.
When the sewn-on portion resulting from such sewing by the overlock sewing machine is disposed on the reverse surface of the garment, however, the fabric becomes thicker at the sewn-on portion (FIGS. 11(a), 11(b)), and the sewn-on portion protrudes beyond the reverse surface of the garment, thereby irritating the skin. In particular, allergic diseases of the skin, for instance atopic dermatitis, have become problematic in recent years. When the skin comes in contact with a garment, the symptoms of such diseases are aggravated due to itching induced by rubbing with the garment. Some improvement can be achieved by turning inside out the underwear or garment that is in contact with the skin, but, even if the protruding sewn-on portion does not come directly in contact with the skin, the sewn-on portion of thick fabric, although lying on the outer surface of the garment, exerts however greater pressure on the skin than other portions of the garment, and the skin becomes irritated, due to sliding, when the individual moves. Wearing the underwear or garment turned inside out is not only troublesome and unaesthetic, but makes it also difficult to fully bring out the intrinsic functionality of such high-functional fabrics as have been developed in recent years, all of which detracts from the value of the garment.
Accordingly, a demand exists for a seam structure for fabric and a sewing method that are aesthetically superior and by virtue of which pieces of fabric can be sewn together smoothly, without a sewn-on portion protruding at the reverse surface of a garment that comes in contact with the skin, and without fabric edges being exposed at the front surface of the garment.
Patent literature 1: Japanese Patent Application Publication No. 2013-34668